1975 FJ40 disk brake upgrade question. Proportioning valve? Yes or no?

[yotamotive]

I've searched but no luck to my specific question. I have a 1975 FJ40 with front drum brakes that I am upgrading to disk. Disk components are from a 76 FJ40. Rear brakes will remain drum. I plan to swap out the master cylinder with a cylinder from a 1986 FJ60. I noticed on the FJ60 master that there is a proportioning valve (see pic) installed just below the master cylinder that the lines run through from the master before heading to the front and rear brakes. My question is...should I include this proportioning valve in my instal? It will complicate line routing some but I assume it can be done with some extra hard or soft lines etc. Any info or experience would be great. Thanks!

 

[Mace]

You are reusing that rusty old master?? I would have purchased a new one personally.

A 1976 master would work just fine. And actually, if you pull the residual valve out of the front circuit of your current master, it'll work just fine as well.

 

[yotamotive]

You are reusing that rusty old master?? I would have purchased a new one personally.

A 1976 master would work just fine. And actually, if you pull the residual valve out of the front circuit of your current master, it'll work just fine as well.

I don't think the rust will have any effect. I don't have a 76 master. Residual valve?

 

[yotamotive]

http://www.ih8mud.com/tech/residvalve.php

 

[Mace]

You have a 75 master right?

Thats the dealio, your 75 master will have it in both circuits of the master. You need to remove the one in the front circuit. then you'll be fine.

and honestly, that amount of rust on the outside of the 60 series master suggests that there may be pitting in the inside of the master.

 

[yotamotive]

You have a 75 master right?

Thats the dealio, your 75 master will have it in both circuits of the master. You need to remove the one in the front circuit. then you'll be fine.

and honestly, that amount of rust on the outside of the 60 series master suggests that there may be pitting in the inside of the master.

Yes....I have a 75 master. So...no proportioning valve needed if I remove the front residual valve on my 75 master? If I just buy a new 76 master...who sells a good one?

 

[cjgoode]

Check rock auto, I just ordered one 10 minutes ago for my 1980, they emailed me abouta closeout on their professional grade one, more then half off. I could not resist, especially since I need one.

 

[Racer65]

You need to add a proportioning valve to the rear brake circuit. That's how it's set up on '76 to '80 FJ40s with front disc / rear drum set up.
I offer a solution that emulates the no-longer-available stock setup that happens to cost a lot less.

 

[Mace]

Rear brakes will remain stock, no reason for the proportioning valve. If he went disk in the rear, then a proportioning valve would be a good idea.

 

[Racer65]

Rear brakes will remain stock, no reason for the proportioning valve. If he went disk in the rear, then a proportioning valve would be a good idea.

It's not a matter of whether the rear brake is stock or not. When you mod a vehicle's brake system, you've changed its chassis dynamics. The front to rear brake bias will no longer be the same as before. An adjustable proportioning valve allows you to accurately tune the rear brake pressure on a modified vehicle so that you don't get rear brake lock-up in hard stop situations.

 

[Mace]

I've personally never done a prop valve on a disk front conversion and never seen the need.

You are increasing the braking power in the front (oversimplified but). The rear stays the same. The prop valve can only reduce the braking power to the rear. From the factory they didn't need to reduce the braking power to the rear, so I see no reason to change that portion. I've done a couple and am not displeased by the conversion at all. I don't see a need for them. That's all.



It does look like a nice product tho!

 

[Racer65]

I've searched but no luck to my specific question. I have a 1975 FJ40 with front drum brakes that I am upgrading to disk. Disk components are from a 76 FJ40. Rear brakes will remain drum. I plan to swap out the master cylinder with a cylinder from a 1986 FJ60. I noticed on the FJ60 master that there is a proportioning valve (see pic) installed just below the master cylinder that the lines run through from the master before heading to the front and rear brakes. My question is...should I include this proportioning valve in my instal? It will complicate line routing some but I assume it can be done with some extra hard or soft lines etc. Any info or experience would be great. Thanks!

By the way the FJ60 valve is really a combination valve with load-sensing features, so it has 4 ports. For the FJ40 that level of sophistication isn't necessary. A regular proportioning valve with 2 ports will work great. That's how Toyota designed it when they went to front disc / rear drums in '76.

 

[Fast Eddy]

From the factory they didn't need to reduce the braking power to the rear

That little guy connected by the lower two bolts of the master cylinder is a factory (disc front, drum rear) proportioning valve.

 

[Mace]

That little guy connected by the lower two bolts of the master cylinder is a factory (disc front, drum rear) proportioning valve.

You are absolutely correct, for a 76+ drum brake rears. 75 and earlier didn't have them.

It gets even worse when you use a 60 series master and proportioning valve system. Those were designed for single Cylinder rear brakes instead of the paired brake cylinders.

IMHO, do the conversion, pull the residual valve and drive it. See if the balance feels good for you of if you want to reduce the rear braking power. If so, grab one of Racer 65's proportioning valves and install it. It is very easy to retrofit after the mod. The disk brake conversion is the hard part. Adding a Proportioning valve after the fact is cake.

 

[Racer65]

Definitely don't go with FJ60 parts for any of this. Consider the serviceability aspect.
The FJ60 valve is almost certainly rusted internally and you cannot get it anymore. When it fails on the trail one day, you will have to re-do this job with a FJ40 MC.

 

[Fast Eddy]

You are absolutely correct, for a 76+ drum brake rears. 75 and earlier didn't have them.

That implies to me that Toyota decided they needed it.

Adding a Proportioning valve after the fact is cake.

It's worth trying it without the prop valve since your lines are all set up. You're going to have to deal with some hard line mods to install the prop valve. That would not be so easy for me since I've never made up any new brake lines.

Slightly off topic: I have an fjz80 master, fj62 front discs and fjz80 rear discs. I use an original prop valve as shown above and it's about right. I might, someday, swap to an adjustable one to get a tiny bit more braking out back.

 

[Mace]

Eddy, Brake Lines are easy, as long as you have a quality tool. The el cheapo tools are 50/50 for failure rates.

 

[Josie'sLandCruiser]

Hi all,

X 2 what Mace wrote.

Folks add a rear proportioning valve to balance out aftermarket rear disc brake conversions that use Chevy Monte Carlo front brake calipers. These calipers produce too much clamping force for a rear brake system. Hence use of the valve to balance the front/rear brake ratio.

Regards,

Alan

I've personally never done a prop valve on a disk front conversion and never seen the need.

You are increasing the braking power in the front (oversimplified but). The rear stays the same. The prop valve can only reduce the braking power to the rear. From the factory they didn't need to reduce the braking power to the rear, so I see no reason to change that portion. I've done a couple and am not displeased by the conversion at all. I don't see a need for them. That's all.

 

[Fast Eddy]

Eddy, Brake Lines are easy, as long as you have a quality tool. The el cheapo tools are 50/50 for failure rates.

I should get one. Marvin needs all new lines on the axles. It's a mess.

 

[yotamotive]

You are absolutely correct, for a 76+ drum brake rears. 75 and earlier didn't have them.

It gets even worse when you use a 60 series master and proportioning valve system. Those were designed for single Cylinder rear brakes instead of the paired brake cylinders.

IMHO, do the conversion, pull the residual valve and drive it. See if the balance feels good for you of if you want to reduce the rear braking power. If so, grab one of Racer 65's proportioning valves and install it. It is very easy to retrofit after the mod. The disk brake conversion is the hard part. Adding a Proportioning valve after the fact is cake.

Thanks for all the input everyone...Im gunna try as Mace suggest above and see how it goes. Less crap to deal with for the instal and lines etc...and it might work fine! I'll report back!